Progressive Addition Spectacle Lenses Research Articles

Bayesian Meta-Analysis of Myopia Control with Multifocal Lenses.

The aim of this study is to provide reliable guidelines for the mean percentage efficacy together with the 95% credibility interval in slowing down progression of myopia by a specific intervention over defined time periods, derived from a substantial number of randomised controlled clinical trials (RCTs) with consistent outcomes. Multifocal spectacles and contact lenses represent interventions with the largest number of RCTs carried out. Our meta-analyses considered 10 RCTs involving 1662 children which have tested the efficacy of progressive addition spectacle lenses (PALs). In a separate model for comparison purposes nine RCTs with 982 children trialling soft multifocal contact lenses (MFCLs) were analysed. Bayesian random-effects hierarchical models were fitted. The highest efficacy in retarding progression of the scaled sphere equivalent refraction was achieved after 12 M follow-up with the mean 28% reduction in progression and the 95% credibility interval between 21% and 35%. For comparison, the 95% credibility interval for the mean efficacy of soft MFCLs at 12 M follow up is 21% to 37%. We conclude that both multifocal spectacle and contact lenses moderately slow down progression of myopia, relative to single-vision spectacle lenses (SVLs) in the first 12 months after intervention. The relative efficacy of PALs tends to weaken after the first 12 months.

Measuring Prism in Progressive Addition Spectacle Lenses

Measuring Prism in Progressive Addition Spectacle Lenses

Evaluating the myopia progression control efficacy of defocus incorporated multiple segments (DIMS) lenses and Apollo progressive addition spectacle lenses (PALs) in 6- to 12-year-old children: study protocol for a prospective, multicenter, randomized controlled trial

BackgroundMyopia is increasing in prevalence and is currently recognized as a significant public health issue worldwide, particularly in China. Once myopia develops, appropriate clinical interventions need to be prescribed to slow its progression. Currently, several publications indicate that myopic defocus (MD) retards eye growth and myopia progression. However, no clinical trials have compared the outcomes of different MD spectacle lenses in the same observational group, especially in mainland China. The aim of the present study is to compare the myopia control efficiency of two different MD spectacle lenses: defocus incorporated multiple segments (DIMS) lenses and Apollo progressive addition lenses (PALs).MethodsThe trial is designed as a 3-year, prospective, randomized, multicenter clinical trial of schoolchildren treated with DIMS lenses and PALs. A total of 600 Chinese primary school children aged 6–12 years will be recruited, and each group is intended to include 300 subjects. The inclusion criteria are myopia between − 1.00 and − 5.00 diopters and astigmatism ≤ 1.50 diopters. The follow-up time points will be 1 month (m), 3 m, 6 m, 12 m, 18 m, 24 m, 30 m, and 36 m. The primary outcome will be determined by the difference between the two groups in cycloplegic spherical equivalent refraction between baseline and the last follow-up visit. The secondary outcome is the axial length, and the exploratory outcomes include ocular biometric measures, peripheral refraction, binocular vision, accommodation, compliance, and the results of questionnaires related to wearing experiences.DiscussionThe present study will be the first randomized controlled trial in myopic primary school children treated with DIMS lenses and PALs in China. The results will indicate whether and how much different MD mechanisms retard myopia progression and axial elongation. In addition, the comparison will provide information on the clinical efficacy and safety of DIMS lenses and PALs, including information related to wearing experiences and visual function.Trial registrationChinese Clinical Trial Registry (ChiCTR), ChiCTR1900025645. Registered on 3 September 2019. http://www.chictr.org.cn/showproj.aspx?proj=42927.

Knowledge, perspectives and clinical practices of Australian optometrists in relation to childhood myopia

BackgroundThe aim was to investigate the understanding of Australian optometrists in relation to myopia, its natural history and associations with vision‐threatening ocular disease, self‐reported clinical diagnosis and management approaches for childhood myopia, engagement with adult caregivers, and utilisation of information to guide practice.MethodsAn online survey was distributed to Australian optometrists (n = 4,124). Respondents provided information about their demographics (for example, gender, age, practice location and modality), myopia knowledge, self‐reported practice behaviours relating to childhood myopia, the information and evidence base used to guide their practice, and perceived extent of adult caregiver engagement in making management decisions for myopic children.ResultsCompleted surveys were returned by 239 optometrists (six per cent completed response rate). Most respondents demonstrated knowledge of the association between high myopia and retinal breaks, retinal detachment and primary open‐angle glaucoma. Optometrists used a range of techniques to diagnose childhood myopia, with a preference for non‐cycloplegic refractive measures. The most common approaches to management were single‐vision distance and progressive addition spectacle lenses, despite most optometrists identifying orthokeratology, low‐dose (0.01%) topical atropine and soft peripheral defocus contact lenses as three potentially more effective therapeutic interventions for modifying childhood myopia progression. Almost 90 per cent of respondents considered increasing time spent outdoors to be beneficial for reducing the rate of myopia progression. The main sources of information used to guide clinical practice were continuing education conferences and events, systematic reviews, and personal experience. Respondents perceived adult caregivers to generally be involved in myopia management decisions, and considered all aspects of myopia education as important.ConclusionCurrent optometric practices reflect the inconclusive nature of several key aspects of the evidence for childhood myopia management. Australian optometrists appear aware of emerging evidence, but are not routinely adopting measures that have not yet received regulatory approval for modulating childhood myopia progression. Clinical guidelines may be of value for assisting practitioners in making clinical decisions based upon the current, best‐available research evidence.

Distortion evaluation method for the progressive addition lens–eye system

Distortion is one of the most significant defects in image optical systems. Herein, a method for comprehensively evaluating progressive addition spectacle lenses based on the modulation transfer function (MTF) and distortion of the lens–eye system is proposed. A lens–eye system is established, and the parameters of the system were simulated and measured simultaneously. The human eye model was compared with and without progressive addition lenses to obtain the image quality of the lenses. It was observed that eyes with different diopters and different lens designs show different trends; however, good improvement was observed in all cases after progressive addition lens correction. In terms of image clarity and deformation, the distant field was caused by a negative distortion value, the near area was caused by a positive distortion value. and the optical distortion was found to be proportional to the diopter. Moreover, the progressive corridor distortion value was minimal. With a larger field of view, the distortion of the lens became larger; thus, when an object was viewed through the lens, large distortion was observed at the edges.

A Review of Current Concepts of the Etiology and Treatment of Myopia.

:Myopia occurs in more than 50% of the population in many industrialized countries and is expected to increase; complications associated with axial elongation from myopia are the sixth leading cause of blindness. Thus, understanding its etiology, epidemiology, and the results of various treatment regiments may modify current care and result in a reduction in morbidity from progressive myopia. This rapid increase cannot be explained by genetics alone. Current animal and human research demonstrates that myopia development is a result of the interplay between genetic and the environmental factors. The prevalence of myopia is higher in individuals whose both parents are myopic, suggesting that genetic factors are clearly involved in myopia development. At the same time, population studies suggest that development of myopia is associated with education and the amount time spent doing near work; hence, activities increase the exposure to optical blur. Recently, there has been an increase in efforts to slow the progression of myopia because of its relationship to the development of serious pathological conditions such as macular degeneration, retinal detachments, glaucoma, and cataracts. We reviewed meta-analysis and other of current treatments that include: atropine, progressive addition spectacle lenses, orthokeratology, and multifocal contact lenses.

Efficacy Comparison of 16 Interventions for Myopia Control in Children: A Network Meta-analysis

To determine the effectiveness of different interventions to slow down the progression of myopia in children. We searched MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov from inception to August 2014. We selected randomized controlled trials (RCTs) involving interventions for controlling the progression of myopia in children with a treatment duration of at least 1 year for analysis. The primary outcomes were mean annual change in refraction (diopters/year) and mean annual change in axial length (millimeters/year). Thirty RCTs (involving 5422 eyes) were identified. Network meta-analysis showed that in comparison with placebo or single vision spectacle lenses, high-dose atropine (refraction change: 0.68 [0.52-0.84]; axial length change: -0.21 [-0.28 to -0.16]), moderate-dose atropine (refraction change: 0.53 [0.28-0.77]; axial length change: -0.21 [-0.32 to -0.12]), and low-dose atropine (refraction change: 0.53 [0.21-0.85]; axial length change: -0.15 [-0.25 to -0.05]) markedly slowed myopia progression. Pirenzepine (refraction change: 0.29 [0.05-0.52]; axial length change: -0.09 [-0.17 to -0.01]), orthokeratology (axial length change: -0.15 [-0.22 to -0.08]), and peripheral defocus modifying contact lenses (axial length change: -0.11 [-0.20 to -0.03]) showed moderate effects. Progressive addition spectacle lenses (refraction change: 0.14 [0.02-0.26]; axial length change: -0.04 [-0.09 to -0.01]) showed slight effects. This network analysis indicates that a range of interventions can significantly reduce myopia progression when compared with single vision spectacle lenses or placebo. In terms of refraction, atropine, pirenzepine, and progressive addition spectacle lenses were effective. In terms of axial length, atropine, orthokeratology, peripheral defocus modifying contact lenses, pirenzepine, and progressive addition spectacle lenses were effective. The most effective interventions were pharmacologic, that is, muscarinic antagonists such as atropine and pirenzepine. Certain specially designed contact lenses, including orthokeratology and peripheral defocus modifying contact lenses, had moderate effects, whereas specially designed spectacle lenses showed minimal effect.

Influence of Presbyopic Corrections on Driving-Related Eye and Head Movements

To investigate whether wearing different presbyopic vision corrections alters the pattern of eye and head movements when viewing and responding to driving-related traffic scenes. Participants included 20 presbyopes (mean age: 56.1 +/- 5.7 years) who had no experience of wearing presbyopic vision corrections, apart from single vision (SV) reading spectacles. Each participant wore five different vision corrections: distance SV lenses, progressive addition spectacle lenses (PAL), bifocal spectacle lenses (BIF), monovision (MV) and multifocal contact lenses (MTF CL). For each visual condition, participants were required to view videotape recordings of traffic scenes, track a reference vehicle, and identify a series of peripherally presented targets. Digital numerical display panels were also included as near visual stimuli (simulating the visual displays of a vehicle speedometer and radio). Eye and head movements were measured, and the accuracy of target recognition was also recorded. The path length of eye movements while viewing and responding to driving-related traffic scenes was significantly longer when wearing BIF and PAL than MV and MTF CL (both p < or = 0.013). The path length of head movements was greater with SV, BIF, and PAL than MV and MTF CL (all p < 0.001). Target recognition and brake response times were not significantly affected by vision correction, whereas target recognition was less accurate when the near stimulus was located at eccentricities inferiorly and to the left, rather than directly below the primary position of gaze (p = 0.008), regardless of vision correction. Different presbyopic vision corrections alter eye and head movement patterns. The longer path length of eye and head movements and greater number of saccades associated with the spectacle presbyopic corrections may affect some aspects of driving performance.

Contrast sensitivity with presbyopic contact lenses

The purpose of the work was to assess the contrast sensitivity function of individuals wearing gas permeable (GP) multifocal contact lenses, soft bifocal contact lenses, and GP monovision lenses. Twenty-six females and six males between the ages of 42 and 65 participated in this study. The study included subjects wearing monovision (N = 8), the Acuvue Bifocal (Johnson & Johnson) (N = 8), Essential GP Multifocal (Blanchard) lenses (N = 8) and progressive addition spectacle lenses (PAL) (N = 8), with PAL wearers forming the control group. Measurements of binocular contrast sensitivity were obtained using the VISTECH 6500 system. Thresholds for each spatial frequency were fit to the equation CS(k) = ak exp(−bk) [1 + c exp(bk)]−1/2, to describe the human contrast sensitivity function. The area under the contrast sensitivity function (CSF) curve was calculated for all four groups and compared. An index of performance was obtained, which was defined as the ratio of CSF with the contact lens correction to the CSF with spectacles. Of the contact lens wearing groups, GP multifocal contact lens wearers had the highest contrast sensitivity at all the spatial frequencies. Soft bifocal contact lens wearers exhibited higher contrast sensitivity than monovision wearers at all spatial frequencies. Subjects wearing GP multifocals had the largest area under the CSF; followed by those wearing soft bifocals, with monovision wearers having the smallest area. GP multifocals have the best visual function at 0.98, soft bifocals have an index of 0.65 and monovision has an index of 0.59. This study quantifies the visual performance of the three lens systems by measuring the area under the CSF curve. In addition, it provides indices of visual function with the contact lenses that will be helpful for analyses and comparisons in future studies.

Technical note: Apparatus for comparison of progressive addition spectacle lenses

Apparatus is described for the measurement of lens power distribution across the surface of a progressive addition spectacle lens. Although the method used is different to that specified in BS 2738-7:1996, the measurements are nevertheless comparable, and are considered sufficiently accurate for making basic comparisons of lens type.

Method for the design and simulation of progressive addition spectacle lenses

A method is described for designing and simulating progressive addition spectacle lenses where the lens design is based on concepts used in single-vision lenses. The computer program based on this method has been found useful for teaching purposes.

Visual detection and adaptation to optically induced curvature distortion Does curvature distortion govern progressive addition lens tolerance?

We attempt to test the hypothesis that patients who fail to tolerate spectacle lenses may do so as a result of their inability to adapt to the induced curvature distortion. Detection of an adaptation to optically induced curvature distortion occurs to a variable extent among a subject population [I. Rock, The Nature of Perceptual Adaptation (Basic Books, New York, 1966)]. Some patients find progressive addition spectacle lenses (PAL's), which are used for the correction of presbyopia, a difficult type of lens to wear, possibly because of the peripheral distortion shown by the lens. [Ophthal. Physiol. Opt. 9, 163 (1989)]. Two presbyopic subject samples (N = 20) of those who successfully adapted and those who failed to adapt to PAL's are presented, and the variation in the detection of and the adaptation to optically induced distortion of a single line are studied with Gibson's wedge prism approach (J. Exp. Psychol. 16, 1 (1933)]. A third sample (N = 20) of prepresbyopes is included as a control group. This study shows that the detection of and the adaptation to optically induced curvature distortion, as assessed with monocular vision, does not govern patient tolerance. Significant age-related differences in the rate of adaptation are noted between presbyopes and prepresbyopes.

Aspheric contact lenses used to control convergence excess

A 15-year-old female patient presented wearing progressive addition spectacle lenses to help control a condition of convergence excess. She was fitted with aspheric, multifocal, rigid gas permeable contact lenses for cosmetic reasons. The lenses were fitted 1.5 dioptres steeper than the flatter keratometer reading, and incorporated an eccentricity value of 0.7. Visual acuities through these lenses were 6/7.5 at both distance and near in each eye. Phorias through the lenses were measured using two methods. The cover test revealed 1 D of esophoria at 6 m and 3 D of esophoria at 40 cm. The Maddox rod also yielded 3 D of esophoria at 40 cm. (Clin Exp Optom 1993; 76.4: 141–142)

Image Evaluation of Ophthalmic Devices

Methods used in the ophthalmic industry to evaluate the optical image quality of correcting lenses have remained the same over many years. This is especially true for single-vision ophthalmic lenses. With the development of new optical designs and materials for correcting refractive errors and presbyopia, new procedures for evaluating lens performance are being explored. One such method is the measurement of the modulation transfer function. Over the last 2 years, we have been measuring modulation transfer functions on a variety of single-vision and bifocal contact lenses, progressive addition spectacle lenses, holographic-diffractive lenses, and intraocular lenses. In this article, the modulation transfer function procedure and its application and results from one study on safety goggles will be presented and discussed.

Progressive addition and variable focus lenses: a review.

This paper reviews recent developments in the field of progressive addition spectacle lenses and variable focus lens systems design. The study is a sequel to the previous analytical work of von Rohr (1916), Graham (1942), and Bennett (1970). A brief history of the work documented by the aforementioned authors is presented. Comparative assessment is undertaken of the most recent patents of progressive addition and variable focus spectacle lenses. A largely verbal description is employed because patent literature is often devoid of mathematical models.